kümmnurk

Kümmnurk is an Estonian word that translates to decagon in English. A decagon is a ten-sided polygon, meaning it has ten edges and ten vertices. Like any polygon, a decagon can be either convex or concave. In a convex decagon, all interior angles are less than 180 degrees, and all diagonals lie entirely within the polygon. A concave decagon has at least one interior angle greater than 180 degrees, and at least one diagonal lies partially or entirely outside the polygon.

A regular decagon is a decagon where all sides are equal in length, and all interior angles are equal. The measure of each interior angle in a regular decagon is 144 degrees. The sum of the interior angles of any decagon, regular or irregular, is (10-2) * 180 degrees, which equals 1440 degrees. The formula for the area of a regular decagon with side length 's' is A = (5/2) * s^2 * cot(pi/10).

The word "kümmnurk" is a straightforward compound word in Estonian, with "kümme" meaning ten and "nurk" meaning angle or corner, thus directly referring to the ten angles of the shape.